Silicon content in rice seedlings to protect rice blast fungus at the nursery stage

摘要

To control rice blast effectively at the nursery stage, the absolute SiO_2 content necessary for rice plants to resist blast disease was investigated using various rice culti-vars and soils. Nine rice cultivars with different complete resistance genesand different degrees of partial resistance were grown on nursery soils amended with silica gel at different rates to change the SiO_2 content of rice plant. The rice seedlings were then inoculated 28 days after sowing with Pyricularia grisea to estimate their blast resistance. In all rice cultivars, the number of lesions was significantly reduced when SiO_2 content increased in the rice seedling; lesions were reduced to 5%-20% of the number on the seedlings grown in soil without silica gel when the seedling SiO_2 content reached 5%. Additionally, the susceptibility to blast disease of rice seedlings grown on eight soils collected from different districts, with varying amounts of silica gel, was compared. The number of lesions decreased significantlywhen the SiO_2 content in the seedlings reached 5%. These results suggest that SiO_2 content of at least 5% in the rice plant can control this disease at the nursery stage under any conditions.